This invention relates to fuel cell power and management systems, and techniques for controlling and/or operating such systems; and more particularly, in one aspect, to fuel cell power and management systems, for example, hydrogen and/or methanol based systems, as well as components, elements and/or subsystems therefore.
Generally, small portable electrical and electronic devices often employ batteries as a power source. However, conventional batteries have limited energy storage capacity and must either be discarded or recharged after they have depleted their limited energy storage capacity. If thrown away, conventional batteries present environmental hazards because of the toxic material used in manufacturing the batteries. If recharged, the recharging process of conventional batteries is time consuming and as the age of these batteries increases it becomes more and more difficult to determine the state of charge of the battery. In this regard, the life becomes unpredictable and unreliable, and so the user often discards the batteries before the useful life is complete, thus incurring additional cost by the user having to carry extra batteries. Applications like professional video cameras, laptop computers, and cell phones often require longer runtimes than conventional batteries can provide.
In addition to battery based systems, fuel cell systems may be employed to provide a portable source of electrical power. In one embodiment, fuel cell systems employ, for example, hydrogen, hydrogen rich gas, hydrogen containing compound or a substance from which hydrogen can be extracted on demand (i.e., a hydride storage cartridge). Such fuel cell systems typically include an anode end for splitting hydrogen atoms into electrons and protons, a current bearing portion providing a pathway for the electrons, a medium such as a proton exchange membrane providing a pathway for the protons, and a cathode end for rejoining the electrons and protons into water molecules in the presence of oxygen. Conventional fuel cells often generate electricity over a longer time period than conventional batteries, provided that the fuel (for example, hydrogen) in the storage container is periodically refreshed. (See, for example, U.S. Pat. Nos. 5,683,828; 5,858,567; 5,863,671; and 6,051,331).